Process and device for drying paper and the like fibrous webs



Jail. 25 1927.

E. v. ASTEN PROCESS AND DEVICE FOR DRYING PAPER AND THE LIKE FIBROUS W855 Filed Feb. 6, 1926 2 s hoot'gs 't 1 Jan. 25, 1927. 5 5, 10

E. V. ASTEN PROCESS AND DEVICE FOR DRYING PAPER AND THE LIKE FIBROUS WEBS Filed Feb. 6, 1926 2 Sheets-Sheet 2 12 5a 5 i i 77 ad 12 Patented Jan. 25, 1927.

UNITED STATES PATENT QFFICE.

EDUARD V. ASTEN, OF EUPEN, BELGIUM.

PROCESS AND DEVICE FOR DRYING PAYER AND THE LIKE FIBROIIS WEBS.

Application filed February 6, 1926, Serial No. 86,615, and in Germany January 30, 1925.

In the drying of paper webs and other webs of fibrous material it has hitherto been customary to passthese webs over steannhcated drying cylinders pressing them against the cylinders by pressure rolls and felts. The moisture contained in the web is then evaporated because of the felts and paper, web coming into contact with the atmospheric air which saturates with the moist vapors and carries them away. The air must, of course, be unsaturated before it enters into action. If the air at disposal is moist it has to be heated in order'to make it water-absorptive. The quantities of heat required to this end are very considerable and they have to'be the larger the higher the percentage of moisture and the atmospheric pressure of the air.- It has already been made out that it would be possible to dry paper and the like webs in a much more economical manner by evaporatingthe water in the webs without the use of the atmospheric air as a moisture-carrier. This kind of evaporation can only be carried out in a vacuum because the temperature would otherwise have to be increased so much that it would deteriorate the quality of the paper. Vacuum drying apparatus have therefore been proposed already comprising an evacuated chamber in which the entire drying device is arranged. These known apparatus possess two serious drawbacks which render their practical use impossible. One drawback resides in that the paper has to be conveyed -into and out of the evacuated chamber through openings which should be closed in an air-tight Way, this however being impossible in actual practice. The other drawback consists in that it is scarcely possible-to convey the paper web automatically through such an evacuated chamber.

My invention has for its object to avoid the aforesaid disadvantages of, the known drying methods and to this end I have devised a method according to which the paper or fibrous web is not conveyed through a closed evacuated chamber but passed over openings of an evacuated chamber so that the web is only on one side under the infill- 9 ence of the vacuum. In order to prevent the paper from being drawn into the evacuatedrhamber the guidlng of the paper over the chamber is effected by means of porous fabric belts on which the paper web is sup- 5 ported.

Someembodiments of the device for carrying out the invention are illustrated dia-.

grammatically in; the accompanying drawings in which: I

I Fig. 1 is a side elevation of the device comprising a plurality of drying cylinders with stationary suction boxes arranged to partly surround the circumference of the cylinders,

Fig. 2 is a section along the line 3-3 of Fig. 1 one larger scale.

The device shown in Fig. 1 includes a plurality of rotary drying cylinders 9 arranged in succession in staggered relation. 5 are suctionboxes in which a vacuum is produced by suitable suction means connected with the boxes by pipes 6. The boxes 5 are of a shape such as to embrace a portion of each drying cylinder 9. The

-side of the boxes 5* turned toward the cylinders is open. The paper web 7 is passed over the drying cylinders 9 and held in contact with the same by porous fabric belts 8 which are preferably endless and guided over rolls 10 some of which may be adjustable to regulate the tension of the belts. In travelling over the cylinders 9 the paper web 7 together with the belts 8 moves past the open sides of the boxes 5 so that they are subjected to the action of the vacuum in the boxes.

The head walls 5 of the boxes 5 are provided ontheir edges, which face the cylinders 9, with a lining 11 of wood or the like. In order to form tight joints between the said edges or linings, respectively, and the belts 8*, there are used endless metal bands 12 which are guided over-rollers 13 at both ends of the boxes 5*. While the belts 8 are of substantially the same Width as the cylinders 9, the bands 12 are narrow and of a width not much larger than the'width of the linings 11, see Fig. 2. The metal bands move in the same direction and with the same speed as the circumference of the drymg cylinders 9. On the one hand, these bands 12 slide on the head walls 5 or their linings 11, respectively, and on the other hand they exert a pressure on the belts 8 so that the latter and the aper web are pressed on the drying cylin ers 9. The belts 8 are thus caused to travel with the cylinders 9 without any relative shifting motion,

and tight joints are formed between the head Walls of boxes 5 and the porous fabric belts 8 by the bands 12. In order to render these joints even more tight :1. suitable lubricant may be provided between thelinings ill and the metal bands 12, Tight joints between the transverse side walls of the boxes 5 and the belts 8 are formed by two of the guide rollers 13- whieh are arranged so as to bear frictionally against the edges of the side walls of the boxes 5 and against the fabric belts 8 which they press against the cylinders 9 together with the paper web 7.

The device shown in Fig. 1 has the special advantage that it may be subsequently applied without any diliiculty to the known paper drying machines comprising rotary drying cylinders.

lit will be understood fromthe above description that the problem ofdrying paper and the'like fibrous webs by evaporating the water contained in the webs, is solved by my invention in a simple manner which may be easily carried out in actual practice. My method and devices besides allow of a considerable saving of heat inasmuchas no drying air is required and the steam withdrawn from the suction boxes may be utilized. for heating or otherindustrial purposes.

Having thus described my invention, what I claim as new and desire to secure by Let-,

ters Patent, is 2- 1. A device for drying paper and the like fabric webs, comprising drying cylinders,.

suction boxes open at one side and arranged with relation to the drying cylinders so as to embrace part of'the circumference of the latter with the open side facing the circumthe. suction boxes.

2. A device for drying paper and the like fabric webs, comprising drying cylinders, suction boxes open at one side and arranged with relation to the drying cylinders so as to embrace part of the circumference of the latter with the open side facing the circumference, porous fabric belts adapted to travel over the drying cylinders between the same and the open side of the suction boxes and to support and carry along with them in a spread condition the web to be dried, transverse guide rollers arranged parallelly of the suction boxes, some of the guide rollers being disposed so as to rotate in close contact with the free. edges of the side walls of the suction boxes and with the fabric belts travelling over the drying cylinders, and endless metal bands at each end of the suction boxes carried .by the guide rollers and adapted to move in the same direction and with same speed as the fabric belts in close contact with the belts and with the edges of the head walls of the suction boxes. In testimony whereof I have signed my name to this specification.

EDUARD v. ASTEN. 

